These open air stoves either use gaseous fuels such as bottled gas for instance, which is a mixture of propane and butane, or some other type of liquid fuel, such as paraffin, ethanol, diesel, methanol or gasoline. Stoves that use bottled gas must be of an approved type, and must fulfil certain requirements with respect to temperature values and emission values in order to be approved. Stoves that have been constructed for liquid fuels do not have to meet corresponding requirements, and hence construction of such stoves has been directed solely towards either gas-fired stoves or solely towards stoves that are fired with liquid fuels. A stove that has been constructed for bottled gas is not suitable for use with paraffin, since the stove has been constructed with a starting point from a liquid fuel source. The type of fuel source for which the stove is constructed controls geometries with respect to vaporisation loop, fuel pipe diameters, nozzle design, the diameter of the nozzle orifice, air holes, etc.
It might be possible to use a stove designed for gaseous fuels with the aforesaid liquid fuels as a fuel source, provided that certain modifications were made with respect to coupling of of the fuel sources, although this would result in a very large difference between the power generated by the stove when using liquid fuel that has a high air requirement (paraffin, diesel) and when using bottled gas, and the stove would be very difficult to ignite. Consequently, a modified construction of this kind is completely uninteresting to the user. From a user aspect, a stove that is operated on gaseous or liquid fuels will preferably be able to heat 1 liter of water to a temperature of 20.degree. C. in a maximum of 3-4 minutes, regardless of the type of fuel used. The stove shall also be compact, so as to enable it to be tucked away in a small space, and will also achieve complete combustion as far as possible, so as to avoid sooting.